Various types of so-called direct-type radiation image capturing apparatuses and so-called indirect-type radiation image capturing apparatuses are being developed. The direct-type radiation image capturing apparatus is a type that generates electric charge by a detection device according to the amount of radiation such as x-ray which is irradiated and converts the generated electric charge to electric signal. The indirect-type radiation image capturing apparatus is a type that converts the irradiated radiation to electromagnetic wave of other wave length such as visible light by a scintillator or the like, and thereafter, generates electric charge by a photoelectric conversion device such as a photodiode according to the energy of the electromagnetic wave which is converted and irradiated, and converts the generated electric charge to electric signal. Here, in the present invention, the detection device in the direct-type radiation image capturing apparatuses and the photoelectric conversion device in the indirect-type radiation image capturing apparatuses are called image capturing devices.
Such types of radiation image capturing apparatuses are known as FPD (Flat Panel Detector), and conventionally, they are integrally formed with a support platform (or a bucky) (for example, see Patent Document 1). However, in recent years, a portable radiation image capturing apparatus which is made to be portable by placing the image capturing device in a housing is developed and is being put to practical use (for example, see Patent Document 2 and 3). Normally, such portable radiation image capturing apparatus has a battery embedded therein.
As for the inner structure of the portable radiation image capturing apparatus, a plurality of image capturing elements 7 are two dimensionally arranged (matrix form) by each of the image capturing elements 7 being arranged in each of small regions which are marked off by a plurality of scanning lines 5 and a plurality of signal lines 6 which are arranged on the substrate 4 so as to cross over each other, as shown in the after-mentioned FIG. 7. Further, each of the image capturing elements 7 is connected to a bias line 9 and each of the image capturing elements 7 is made to be conductive by reverse bias voltage being applied from the reverse bias power source 14 via the bias lines 9. Thereby, each of the image capturing elements 7 is made to be in an image capturing state.
Moreover, in the radiation image capturing, when radiation is irradiated to the radiation image capturing apparatus, electric charge is generated in the image capturing elements 7 according to the amount of radiation which is irradiated and the electric charge of each of the image capturing elements 7 is read by the reading circuits 17, and then, each of the read electric charge is amplified by the charging/voltage conversion or the like to be taken out as an electric signal.
However, when each of the image capturing elements 7, the reading circuits 17 and the like are made to be conductive for the radiation image capturing, relatively large amount of power is to be consumed when considering the radiation image capturing apparatus as a whole. In the above mentioned radiation image capturing apparatus which is integrally formed with the support platform or the bucky, the situation where the radiation image capturing cannot be carried out will not occur even when a relatively large amount of power is being consumed because power is supplied constantly via the support platform or the bucky. However, in the battery embedded type portable radiation image capturing apparatus, the battery will die when a large amount of power is consumed and there will be problems that radiation image capturing cannot be carried out consecutively, that the battery needs to be charged frequently and the like.
In view of the above problems, in Patent Document 4, there is suggested an example of a radiation image capturing apparatus which is integrally formed with a support platform and the bucky. However, this example of a radiation image capturing apparatus is an image capturing apparatus which is structured by having separate power supply units for supplying power to each of the sensor region in which the image capturing elements 7 are provided and to the reading circuits 17 and the like, the radiation image capturing apparatus supplies power to the image capturing elements 7 and the like in the sensor region first, and then, supplies power to the reading circuits 17 and the like.